Expansible anchor



Jan. 12, 1954 J. L. HILL EXPANSIBLE ANCHOR Filed March 8, 1951 (itt negJAMES L. HILL "l ESI,

' this assuring Patented Jan. 12, 1954 James L. Hill, Wichita,

tion of Delaware Kans., assgnor to Boeing Airplane Company,.Wichita,Kans., a, corpora-- Application March s, 1951 serial N0..214,44a

(c1. vr-pzvi 3 Claims. 1.

This invention relates toa special tool for aide ing in thecountersinking of holes in heavy gage metal, and more particularly to anexpansible anchor which can be passed through a hole to be countersunk,automatically expanded on the opposite side of the workpiece to preventits withdrawal therefrom, and thus used as an anchor for the applicationof the required axial force to the countersinking bit. The type ofcountersinking tool with which the specific an` chor constituting thepresent invention may be used is fully described and illustrated in my4pending patent application Serial No. 199,071, iiled December 4, 1950.This typeof countersinking tool includes an axially bored countersinkingbit which rotates about .an axially movable draw bar Which extendsoutward beyond the working end of the bit, and to which an axialco-untersinking force may be applied mechanically.

It is an object of this invention to provide an anchor suitable forinstallation on the free end panded, the drawbar and countersink bitcentered with relation to the hole, and the counterof the drawbar ofsuch a countersinking tool to aid in -forcing the countersink bitaxially into ther workpiece to accomplish the countersinking cut.

It is a further object toprovide an anchor ofA this type which utilizesthe principle of the vvedgev or inclined surface, and which`is expandedin diameter by a slight axial movement of its drawbar in a directionopposite the direction ofV its original insertion into a Another objectis to provide an anchor which, when expanded, will perfectly center thedraw bar with relation to the hole to be countersunk,

hole -in a workpiece.

sink cut and the hole in the workpiece.

Another object of this invention is to provide an anchor which Willautomatically contract to its normal diameter when it is moved away fromanchoring contactl with the workpiece surface, thus permitting it to beeasily withdrawn through the hole after the countersinking cut has beenmade.

The invention, together with other objects, will be more clearlyunderstood when the following description is read in connection. withthe ac.u companying drawings, in which.:

Fig. l is a vertical sectional view of a preferred form of the inventionattached to the drawbar of a countersinking tool, a workpiece beingshown fragmentarily, and the anchor being shown in its contractedcondition just after it has been passed through the hole to becountersunk;

Fig. 2 is a similar view showing the anchor exconcentricity between thecountersink bit ready to begin its cutting-operation; and

Fig. 3 is aperspective view of an expansible sleeve which constitutes apart ofthe invention.

Referring to the drawings, it will be seenY that this anchor includes aninclined surface type expander II), a longitudinally split expansiblesleeve II, and a drawbar I2 seated axially in the expander and adaptedto serve as the means for moving the expander axially with relation tothe sleeve. It should be noted thatl the drawbar or a similar functionalelement actuallyr Yconstitutes an essential'part of this invention.

As to details of construction, the expander is generally cylindrical andhas an enlarged head I'3, an adjacent intermediate cylindrical slidewayI4` of reduced' diameter, an elongated cylindrical portion I5 ofstillsmaller diameter, anda frusto-conical end It..v The expander has acentral bore I] which is threaded to receive one end ofY the drawbar`I2. The head end of this ex-l pander` is counterbored to receive a hardfibre washer I8 which is locked in position by rolling the edge` ofthecounterbore shoulder inward, as atA I9". The diameter ofthe head I3 issuchas to permit it toV pass through the hole in workpiece 20. The librewasher serves as a friction lock to prevent the Adrawbar I2 frombackingV out of its seat in the expander .during the repeated expansionand contraction of the anchor.

The sleeve Il is.. generally cylindrical but has anannular shoulder `2l,a slightly tapered exterior surface 22, and a truste-conical exteriorend 'surface 23. It has a plurality of radially disposed longitudinalslots extending from its end 2,3` to. a` point near its opposite ends,and the major part of its Wall is-thus divided into a plurality. ofsector shaped segments eachof which is inherently resilientdue tothecharacteristics of themetal. of which the sleeve is made, and. can

therefore be moved radially outward from the sleeve axis. The-externaldiameter of this sleeve is no greater than theexternal diameter of theexpander head I3.

Internally the sleeve IIv has a normally cylindrical bore- 24 ofVadiameter to slidably seat on thecy-lindrical slideway I4,- Zat itsoppositeend to .slideably embrace the drawbar I2, and a connectingconical bore 26 adapted to contact and cooperate with the conicalexterior surface I6 of the expander. As shown in Fig. 1, tapered atsubstantially the same angle when the small end of the sleeve is fullycontracted.

asmaller` central bore these two surfaces IG'and 26 are Operation Fig. 1shows the anchor after having passed through the hole in workpiece 20from its upper side. The anchor is next moved to an eccentric positionwith relation to the hole so that a portion of annular shoulder 2|underlies and is in contact with a portion of the workpiece surfacesurrounding the hole, as indicated at 21.

Drawbar I2 is next moved slightly axially in the direction of the arrow.Since the sleeve is held by the workpiece against movement in thisdirection, the expander moves in a sleeve penetrating direction, and theconical expander surface I6 (Fig. 2) cams on the sleeve surface 26 andforces the individual segments of the sleeve radially outward,increasing the exterior diameter of the sleeve surface 22 until it isforced firmly against the wall of the hole in the workpiece. The degreeof outward movement of each individual segment is identical because theconical surfaces I6 and 26 are concentric to the longitudinal axis ofdrawbar I2. Simultaneously the diameter of annular shoulder 2I isincreased, as shown in Fig. 2, so that the entire surface of theshoulder is in contact with the workpiece surface surrounding the hole.A firm anchor against movement of the anchor assembly in the directionof arrow 28 is thus created.

To release the described anchor it is only necessary to move the drawbarslightly away from its contact with the workpiece. The inherentresilience in the individual segments of the sleeve force the surface 26to cam against the contacting surface of the expander. This cammingaction moves the sleeve longitudinally on slideway I4 and the entiresleeve returns to the position Yshown in Fig. l, with all segmentsretracted;

The entire anchor assembly may then be withdrawn from the hole in theworkpiece,

It should be noted that the diameters of both expander and sleeve shouldbe varied with the diameter of the hole in which it is desired to anchorthe end of the drawbar. The cooperating inclined surfaces I6 and 26should be smooth, and the shoulder between surface i6 and normallycylindrical surface I should preferably be gently rounded, as shown, tofacilitate the camming action between the two surfaces.

While this anchor has been described in connection with a countersinkingtool which has a countersink bit 29 movable axially as well asrotationally on drawbar I2, it will be apparent that it can be used onan end of any elongated element which it is desired to anchor in adrilled hole in a fixed part.

Having described the invention with sufdcient clarity to enable thosefamiliar with this art to construct and use it, I claim: n

1. A normally contracted expansible anchor for a draw bar adapted to bepassed axially through a hole in a work piece and to expand and anchortherein in response to draw bar thrust applied in a withdrawingdirection, said anchor comprising: a generally cylindrical sleeveexpander rigidly secured concentrically on the draw bar; an externalannular shoulder near the outer end of said expander facing thedirection of draw bar pull; an external frusta-conical camming surfaceat the inner end of the expander, also facing the direction of draw barpull; an external cylindrical surface intermediate the ends of theexpander; a generally cylindrical sleeve having its outer end slidablyand concentrically seated on and encompassing the said cylindricalsurface of said expander for movement axially with relation thereto; anexternal annular shoulder near the inner end of said sleeve facing saidinner end and in the direction of draw bar pull; a plurality ofcircumferentially spaced longitudinally disposed slots in said sleeveextending from its inner end to a point near its outer end, dividing theslotted portion of the sleeve into a plurality of radially exiblelingers, the free ends of which project in the direction of draw barpull; and an internal frusto-conical camming surface within the sleevenear its inner end for cooperation with the similar camming surface atthe inner end of the expander to force the inner ends of said fingersradially outward in response to movement of the expander with relationto the sleeve in the direction of draw bar pull.

2. The invention described in claim 1 in which the external diameter ofthe outer end of said sleeve is substantially equal to the externaldiameter of the annular shoulder at the outer end of the expander.

3. A normally contracted expansible anchor adapted to be fixed on anelongated draw 'bar and carried thereby, and capable of passing axiallythrough a hole in a work piece with the draw bar and expanding inresponse to draw bar thrust in a withdrawing direction to anchor thedraw bar in the work piece hole, said anchor comprising: an elongatedsubstantially cylindrical expander fixed on the draw bar and having afrusto-conical inner end surface and an enlarged annular externalshoulder near its outer end; and a normally contracted expansible sleevehaving an annular outer end carried by and slidable axially along thecylindrical portion of said expander, that portion of the sleeve fromits annular outer end to its inner end being divided longitudinally intoa plurality of relatively narrow inherently resilient lingers, saidsleeve having an exterior annular shoulder near its inner end forcontacting a work piece surface when said fingers are expanded radiallyoutward, said sleeve also having an interior conical surface near itsinner end to cooperatively cam on the frusto-conical surface of saidexpander in response to a sleeve penetrating movement of the expanderresulting from draw bar pull, the maximum outside diameter of saidsleeve while its fingers are in contracted position being no greaterthan the diameter of the hole in which the draw bar is to be anchored.

JAMES L. HILL.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,364,489 Edelblut Jan. 4, 1921 1,721,310 Miller July 16, 19291,851,421 Conklin Mar. 29, 1932 2,393,587 Bugg et al. Jan. 29, 19462,479,660 Wright Aug. 23, 1949

